This invention relates to a method of locating and determining the position of wireless mobile stations in a communication network. For the purposes of this specification, such a communication network will be referred to as an Opportunity Driven Multiple Access (ODMA) network.
The determination of location is useful to service providers in the provision of location based services to subscribers to a communication network. Such services include, for example, the provision of driving direction instructions, vehicle tracking, relevant regional information and available applications; while also enabling categorization of subscribers for various purposes and for billing differentiation.
In addition, various regulatory authorities around the world now require that service providers of wireless telephone networks must be capable of locating the users of the wireless telephones in order to facilitate emergency call processing.
These regulations mandate that the position of such users must be established to within predefined distances of their actual physical location. In the United States of America, for example, the Federal Communications Commission promulgated wireless Enhanced 911 (E911) rules require that service providers must be able to locate at least two-thirds of the users of wireless telephones on their networks within 125 meters of the users' actual physical locations.
The location of a wireless station in a network is generally determined using either network based location systems or station based location systems. Network based location systems typically utilize techniques that involve the triangulation of signals between the wireless stations and fixed position base stations or access points, which act as communication ports between the wireless stations and the network. Station based systems may incorporate other technologies such as Global Positioning System (GPS) receivers that may be built into the wireless devices of the stations or used in combination with the devices.
It is likely that the need for service differentiation will grow in relevance and that emergency regulation will possibly be extended to wireless devices other than telephones. Consequently, accurate location and positioning of the user stations has now become an essential feature in wireless networking environments. At present it is difficult to locate certain of these devices, such as in the VOIP (Voice Over Internet Protocol) environment, without using positioning equipment together with the wireless unit as there is no fixed relationship between the VOIP device and the geographic position. In addition, positioning technologies are subject to limitations that may render the stations undetectable.
It is an object of the invention to provide accurate, continuous location and positioning information relating to wireless mobile stations, including VOIP and other traditionally undetectable devices, using a network based methodology that is not dependent on base stations and access points.